Write the sum as a product:
$\displaystyle {\cos{{\left({24.9}{s}\right)}}}+{\cos{{\left({7.7}{s}\right)}}}=$ Preview Question 6  
Note:  coefficients inside of the trigonometric functions should be entered as (simplified) decimal values—do not enter fractions inside of the trig functions...else they will be marked incorrect by the system.  For example, if your answer is $\displaystyle \frac{{11}}{{2}}$, enter 5.5 instead of 11/2.